Negative pressure treatment including mechanical and chemical pump

ABSTRACT

A negative pressure assembly includes a drape, a sealing element, a reactor, and a mechanical pump assembly. The drape covers a dressing site on a patient and seals against the skin upon application of a vacuum while maintaining a negative pressure underneath the drape. When applied to the skin, the sealing element cooperates with the drape to define an enclosed volume covered by the drape and surrounded by the sealing element. The reactor is located with respect to the drape and the sealing element to be in fluid communication with the enclosed volume when the drape is covering the dressing site and is configured to react with and consume a selected gas found in air. The mechanical pump assembly is connectable to the enclosed volume and has a pump chamber in fluid communication with the enclosed volume to draw air from the enclosed volume into the pump chamber.

BACKGROUND

Negative pressure therapy is a therapeutic treatment that utilizesnegative pressure for skin treatments and restorative purposes. Negativepressure is a term used to describe a pressure that is below normalatmospheric pressure. Negative pressure therapy is utilized for severalsites on the skin, such as a wound or an incision. Furthermore, negativepressure therapy is useful to manage wounds with complex healingconcerns. Additionally, negative pressure therapy could also be used forcosmetic purposes like removing wrinkles.

Generally, negative pressure therapy is achieved by maintaining areduced pressure beneath a dressing on a dressing site. A vacuumgeneration source, such as a pump, applies reduced pressure to theinside of the dressing on the dressing site. However, when a vacuumsource that operates using a chemical reaction is first activated, adesirable negative pressure may not be obtained for the first fewminutes of the operation of the vacuum source. As a result, if thedressing is not properly sealed at the beginning of the negativepressure therapy, an indication that the dressing is not sealed may notbe noticeable for a few minutes. Furthermore, when a reduced pressure isfinally obtained, the negative pressure may be susceptible to decreasingbelow a target pressure range for the negative pressure therapy (e.g.,too much vacuum is applied on the skin). When the negative pressuredecreases below the target pressure range, the dressing may beuncomfortable for the patient.

SUMMARY

In view of the foregoing, a negative pressure assembly includes a drape,a sealing element, a reactor, and a mechanical pump assembly. The drapecovers a dressing site on a patient and when sealed against the skinupon application of a vacuum is capable of maintaining a negativepressure underneath the drape. When applied to the skin, the sealingelement cooperates with the drape to define an enclosed volume coveredby the drape and surrounded by the sealing element. The reactor isconfigured to react with and consume a selected gas found in air, and islocated with respect to the drape and the sealing element to be in fluidcommunication with the enclosed volume when the drape is covering thedressing site. The mechanical pump assembly is fluidly connectable tothe enclosed volume and has a pump chamber in fluid communication withthe enclosed volume to draw air from the enclosed volume into the pumpchamber.

The negative pressure assembly described above may further include adressing including the drape and an absorbent material. Additionally,the reactor may be disposed in the dressing. Furthermore, a relief valvemay be disposed on the dressing. The relief valve is in fluidcommunication with the enclosed volume and ambient. When a pressuredifferential between ambient and the enclosed volume is outside apredetermined pressure range, the relief valve allows gas from ambientto enter the enclosed volume.

The mechanical pump assembly can be connected to the dressing, and thepump chamber of the mechanical pump assembly is in fluid communicationwith the enclosed volume. The mechanical pump assembly can be connectedto the dressing via a valve, a fitting, or a hose. The valve may beconfigured to allow gas to exit through the valve and into the pumpchamber of the mechanical pump assembly while also preventing ambientair from entering into the enclosed volume through the valve.Alternatively, the valve may be a bidirectional valve configured toallow gas to exit through the valve when ambient pressure is below thatof the enclosed volume and to allow gas from ambient to enter theenclosed volume through the valve when the pressure differential betweenambient and the enclosed volume is outside a predetermined pressurerange. Furthermore, the mechanical pump assembly may include amanually-actuated actuator and a biasing mechanism operatively connectedwith a movable pump element. When the manually-actuated actuator isactuated, the biasing mechanism moves the movable pump element. Inresult, air is drawn into the mechanical pump assembly. The biasingmechanism can be a spring, and the movable pump element can be a piston.

The negative pressure assembly described above may further include achemical pump assembly including a chemical pump housing having achamber. In this embodiment, the reactor is positioned in the chamber ofthe chemical pump housing instead of the dressing. Furthermore, thechemical pump assembly may include a diaphragm which moves toward thechamber to indicate when the chamber is under negative pressure.Additionally, the relief valve may alternatively be disposed on thechemical pump assembly instead of the dressing or may remain on thedressing.

The chemical pump housing may be connected to the dressing via a valve,a fitting, or a hose. Furthermore, the chemical pump assembly may beconnected to a second dressing covering a second dressing site via asecond valve, a second fitting, or the hose. The hose may be Y-shaped toconnect the chemical pump assembly to the dressing and the seconddressing at the same time. When the chemical pump housing is connectedto the dressing, the chamber of the chemical pump assembly is in fluidcommunication with the enclosed volume. The hose may be retractable intothe chemical pump assembly. Alternatively, the hose can be wound arounda wrap element disposed on the chemical pump assembly. Also, when thechemical pump assembly is connected with the dressing via a fitting, themechanical pump assembly may also be connected with the dressing via thefitting when the chemical pump assembly is not connected to the dressingvia the fitting. Alternatively, the chemical pump assembly and themechanical pump assembly may be connected to the dressing via separatevalves, fittings, and/or hoses.

In still another embodiment, the mechanical pump assembly can beconnected to the chemical pump assembly. In result, the pump chamber ofthe mechanical pump assembly is in fluid communication with the enclosedvolume via the chemical pump assembly. The mechanical pump assembly canbe connectable with the chemical pump housing via a valve, a fitting, ora hose. In the embodiment with the valve, gas can exit through the valveand into the pump chamber while also preventing ambient air fromentering the chamber through the valve.

A negative pressure assembly according to another embodiment includes adrape, a sealing element, a valve, and a mechanical pump assembly. Thedrape covers a dressing site on a patient and is capable of maintaininga negative pressure underneath the drape when sealed against thepatient's skin upon application of a vacuum. The sealing elementcooperates with the drape when applied to the skin to define an enclosedvolume covered by the drape and surrounded by the sealing element. Thevalve is disposed on the drape and has a first operating state in whichgas exits the enclosed volume through the valve and a second operatingstate in which gas is precluded from exiting the enclosed volume throughthe valve. The mechanical pump assembly includes a pump chamber fluidlyconnectable to the enclosed volume through the valve when the valve isin the first operating state. The mechanical pump assembly is alsoconfigured to draw air from the enclosed volume into the pump chamberwhen fluidly connected with the enclosed volume.

The negative pressure assembly may further include a dressing includingthe drape, the sealing element, and an absorbent material. Themechanical pump assembly is connectable to the dressing through thevalve so that the pump chamber is in fluid communication with theenclosed volume. The negative pressure assembly may also include areactor located with respect to the drape and the sealing element sothat the reactor is in fluid communication with the enclosed volume whenthe drape is covering the dressing site. The reactor reacts with aselected gas found in air and consumes the selected gas. In oneembodiment, the reactor is disposed in the dressing. In anotherembodiment, the negative pressure assembly further includes a chemicalpump assembly having a chemical pump. housing in which the reactor isdisposed in the chemical pump housing.

Furthermore, a relief valve may be disposed on the dressing. The reliefvalve is in fluid communication with the enclosed volume and ambient.The relief valve allows gas from ambient to enter the enclosed volumethrough the relief valve when a pressure differential between ambientand the enclosed volume is outside a predetermined pressure range.Alternatively, the valve may be a bidirectional valve that allows gas toexit through the valve when ambient pressure is below that of theenclosed volume and allows gas from ambient to enter the enclosed volumethrough the valve when the pressure differential between ambient and theenclosed volume is outside a predetermined pressure range. Thepredetermined pressure range may be between 50 and 200 mmHg belowatmospheric pressure.

Additionally, the mechanical pump assembly may include amanually-actuated actuator and a biasing mechanism operatively connectedwith a movable pump element. The actuation of the manually-actuatedactuator results in the biasing mechanism moving the movable pumpelement. In result, air is drawn into the mechanical pump assembly. Thebiasing mechanism may be a spring, and the movable pump element may be apiston. A hose may also be retractable into the mechanical pumpassembly. Alternatively, the hose may be wound around a wrap element onthe mechanical pump assembly. The mechanical pump assembly may furtherbe connected to a second dressing covering a second dressing site via avalve, a fitting, or a hose.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a negative pressure kit.

FIG. 2 is a schematic cross-sectional view of a dressing and amechanical pump assembly of the negative pressure kit according to oneembodiment.

FIG. 3 is a perspective view of a dressing and a mechanical pumpassembly.

FIG. 4 is a perspective view of the dressing in FIG. 3 and a chemicalpump assembly prior to connection of the chemical pump assembly to thedressing.

FIG. 5 is a schematic cross-sectional view of the chemical pump assemblyaccording to one embodiment.

FIG. 5A is a schematic cross-sectional view of the chemical pumpassembly according to yet another embodiment.

FIG. 6 is a schematic cross-sectional view of the mechanical pumpassembly before actuation.

FIG. 7 is a schematic cross-sectional view of the mechanical pumpassembly after actuation.

FIG. 8 is a perspective view of the dressing and the chemical pumpassembly after connection of the chemical pump assembly to the dressing,but prior to negative pressure in a therapeutic range underneath thedressing.

FIG. 9 is a perspective view of the dressing, the chemical pump assemblyand the mechanical pump assembly (in schematic cross-section) afterconnection of the chemical pump assembly to the dressing and connectionof the mechanical pump assembly to the chemical pump assembly, but priorto actuation of the mechanical pump assembly.

FIG. 10 is a perspective view of the dressing, the chemical pumpassembly and the mechanical pump assembly after connection of thechemical pump assembly to the dressing and connection of the mechanicalpump assembly to the chemical pump assembly, and after actuation of themechanical pump assembly after actuation.

FIG. 11 is a perspective view of the dressing and the chemical pumpassembly after connection of the chemical pump assembly to the dressing,and after negative pressure in a therapeutic range has been achievedunderneath the dressing and a diaphragm inverts toward a chamber in thechemical pump assembly.

FIG. 12 is a perspective view of the dressing, the chemical pumpassembly and the mechanical pump assembly before connection of thechemical pump assembly to the dressing and after connection of themechanical pump assembly to the dressing, but prior to actuation of themechanical pump assembly.

FIG. 13 is schematic cross-sectional view of a portion of a chemicalpump housing including a wrap element.

FIG. 14 is a perspective view of the chemical pump assembly and thedressing and a second dressing after negative pressure in a therapeuticrange underneath the dressing according to another embodiment.

FIG. 15 is a perspective view of the mechanical pump assembly (inschematic cross-section) and the dressing after connection of themechanical pump assembly to dressing, but before the actuation of themechanical pump assembly according to still another embodiment.

DETAILED DESCRIPTION

FIG. 1 depicts a negative pressure kit 10 useful for negative pressuretherapy. Negative pressure described herein is pressure belowatmospheric pressure. The negative pressure kit 10 includes a tray kit12 and a negative pressure assembly. In the embodiment depicted in FIG.1 , the negative pressure assembly includes at least one dressing 14, achemical pump assembly 16, and a mechanical pump assembly 18.

The tray kit 12 comprises a top cover 20 and a bottom cover 22. At leastone recess 24 may be provided on the bottom cover 22 for storing the atleast one dressing 14, the chemical pump assembly 16, and the mechanicalpump assembly 18. Spacer walls 26 can be added to maintain space betweenthe top cover 20 and bottom cover 22 when the tray kit 12 is closed. Thespacer walls 26 can at least partially surround the perimeter of the atleast one recess 24. The bottom cover 22 may further include securingelements for securing the components in the at least one recess 24.Also, the tray kit 12 may comprise a closing element for keeping the topcover 20 and bottom cover 22 closed, and may further include lockingattachments for locking the tray kit 12 when the tray kit 12 is closed.

With reference to FIG. 2 , the dressing 14 is placed over a dressingsite 28 on a patient's skins. The dressing site 28 can be, but is notlimited to, a wound, an incision, or skin where there is no wound orincision. In the illustrated embodiment, the dressing 14 includes adrape 40, a wicking or absorbent element 42 and a fitting 44. Thedressing 14 can include further components, such as a sealing element46, and can be similar construction to the dressings described in U.S.application Ser. No. 16/114,813 and/or PCT/US2016/059364. The drape 40can be made from a flexible material and can be made from a thin,flexible elastomeric film. Examples of such materials includepolyurethane or polyethylene films. The drape 40 can include at leastone opening 48 (see FIG. 1 ), which can cooperate with the fitting 44.The drape 40 in the illustrated embodiment is a thin film capable ofmaintaining a negative pressure underneath the drape 40 when sealedagainst the skin upon application of a vacuum when the opening 48 is notin communication with ambient.

The drape 40 further comprises a drape top 52 and a drape edge 54. Thedrape top 52 and the drape edge 54 can be made from one continuous pieceor multiple pieces fused together. The drape edge 54 is placed aroundthe dressing site 28, and the drape top 52 covers the dressing site 28.The drape 40 can be made in a variety of shapes and sizes to cover avariety of dressing sites 28. The opening 48 extends through the drapetop 52.

With continued reference to FIG. 2 , the sealing element 46 cooperateswith the drape 40 and the skin S to create an enclosed volume 60 definedbetween the drape 40 and the dressing site 28 and surrounded by thesealing element 46. The sealing element 46 can be separate from thedressing 14 or a component of the dressing 14. The sealing element 46functions like a gasket, as the sealing element 46 prevents fluid(including air) from escaping between the drape 40 and the skin S. Whenproperly sealed, air or select gases found in air can selectively exitthe dressing 14 through the at least one opening 48 and fitting 44.Thus, the sealing element 46 helps maintain negative pressure within thedressing 14. The sealing element 46 can be made from a material such assilicone or a hydrogel material.

The dressing 14 may further include a wound contact layer 68. The drapetop 52 covers the wound contact layer 68 and/or the wicking or absorbentelement 42. The wound contact layer 68 can be made of an elastomericmaterial, such as a polymeric material that has rubber-like properties.Furthermore, the wound contact layer 68 can be an elastomeric materialthat is a thin, flexible elastomeric film. Some examples of suchmaterials include a silver coated nylon, a perforated silicone mesh, orother materials that will not stick to the patient's tissue. The woundcontact layer 68 contacts the dressing site 28. The wound contact layer68 can include at least one opening to cooperate with the wickingelement 42 to retain exudate traveling from the dressing site 28 intothe enclosed volume 60. The sealing element 46 can also be disposed onthe side of the wound contact layer 68 that contacts the dressing site28 (or the wicking element 42 if the wound contact layer 68 is notincluded).

A drape release liner (not shown) is disposed on the bottom surface ofthe drape edge 54. The drape release liner is removed before thedressing 14 is applied to the dressing site 28. When the drape releaseliner is removed, an adhesive 66 on the bottom surface of the drape edge54 is exposed. As the dressing 14 is placed on the patient, the adhesive66, which can be an acrylic-based adhesive that is distinct from thesealing element 46, secures the drape edge 54 to the patient's skin Saround the dressing site 28. Thus, contact is maintained between thedrape edge 54 and the skin S.

The wicking or absorbing element 42 is made from an absorbent materialthat is capable of absorbing exudate from the dressing site 28. Thewicking element 42 can be made from super absorbent polymers, absorbentbeads, foams, or natural absorbents. Also, the wicking element 42 canprovide appropriate voids for gases found in air so that reducedpressure can be maintained. For example, the wicking element 42 can bemade from a relatively more rigid foam as compared to the drape 40 sothat gas voids are maintained while absorbing exudate from the wound.The wicking element 42 could also be made from the superabsorbentpolymers described above that expand and form gas voids, for examplebetween adjacent beads, to provide aforementioned volume control. Thewicking element 42 can also be a hydroactive wound pad available underthe trademark Vilmed®, which chemically absorbs exudate and precludesthe exudate from passing through the wicking element toward the vacuumsource unlike a sponge.

The dressing 14 can also include an air permeable liquid imperviousmembrane 70 covering the opening 48 in the drape top 52. In anembodiment, the air permeable liquid impervious membrane 70 is disposedon the bottom surface of the drape top 52. Air is allowed to travelthrough the air permeable liquid impervious membrane 70, whereas liquidis prevented from traveling through the air permeable liquid imperviousmembrane 70. Therefore, exudate is not able to flow through the airpermeable liquid impervious membrane 70. In another embodiment, the airpermeable liquid impervious membrane 70 is disposed on the top surfaceof the drape top 52. Furthermore, FIG. 2 depicts a chemical pump 82 inthe form of a reactor disposed in the dressing 14 beneath the drape 40.The chemical pump 82 can be located elsewhere, which will be describedin more detail below.

FIG. 3 depicts the dressing 14 connected with the mechanical pumpassembly 18 via a hose 62 (schematically depicted). When the mechanicalpump assembly 18 is connected to the dressing 14, the mechanical pumpassembly 18 is in fluid communication with the enclosed volume 60 viathe fitting 44 in a manner described in more detail below. Actuation ofthe mechanical pump assembly 18 draws air from the enclosed volume 60through the opening 48, fitting 44, and hose 62 into the mechanical pumpassembly 18. As such, the sealing of the dressing 14 against the skin Scan be checked in that the drape 40 would be drawn toward the skin S.The hose 62 can then be removed from the fitting 44, which would allowair into the enclosed volume 60 resulting in the enclosed volume 60returning towards atmospheric pressure.

FIG. 4 depicts the dressing 14 and the chemical pump assembly 16. Thechemical pump assembly 16 includes a chemical pump housing 80, achemical pump 82 (shown in phantom in FIG. 4 ) positioned in a chamber84 (see FIG. 5 ), and a lower opening 86 disposed on the bottom of thechemical pump housing 80 and in fluid communication with the chamber 84.When connected with the fitting 44, the chamber 84 in the chemical pumphousing 80 is in fluid communication with the enclosed volume 60 via thelower opening 86, the at least one opening 48, and the fitting 44 on thedrape 40. The chemical pump assembly 16 applies reduced pressure on theinside of the dressing 14 in a manner that will be described in moredetail below.

The chemical pump 82 in the chemical pump assembly 16 is a reactorconfigured to react with a selected gas found in air. The chemical pump82 is located with respect to the drape 40 and sealing element 46 sothat the chemical pump 82 can be in fluid communication with theenclosed volume 60. The chemical pump 82 consumes the selected gas fromthe enclosed volume 60, thereby removing the gas and reducing the gaspressure. Examples of reactors that can be used in the chemical pumpassembly 16 are described in US 2014/0109890A1 and PCT/US2016/059364. Inthe case of a therapeutic negative pressure system, utilized for woundcare, the range of reported operating pressures, relative to standardatmospheric pressure of 760 mmHg, are −50 mmHg to −200 mmHg (absolutepressure of 560 to 710 mmHg). When the pressure is less than 560 mmHg,the at least one dressing 14 can become uncomfortable for the patient.When the pressure is above 710 mmHg, the negative pressure therapy maynot be as effective compared to pressures below 710 mmHg. However,smaller target pressure ranges within the 560 to 710 mmHg may bedesired. Thus, the reactor 82 can be configured to maintain a reducedpressure range within a predetermined target pressure range.

The chemical pump assembly 16 is configured to maintain a predefinedchamber volume, as the chemical pump 82 consumes the selected gas fromthe enclosed volume 60. The size of the reactor 82 is dependent on thevolume of the chamber 84, the hose 62 and the enclosed volume 60, amongother factors. In another embodiment, the reactor 82 can be disposed inthe dressing 14 instead of the chemical pump assembly 16, as depicted inFIG. 2 . As a result, the chemical pump assembly 16 may be eliminated inthe method of applying negative pressure within the dressing 14.

In the illustrated embodiment of FIG. 5 , an upper opening 90, in whicha first valve 92 is disposed, is provided on the top of the chemicalpump housing 80. Additionally, the upper opening 90 and first valve 92can be disposed on a side of the chemical pump housing 80 and elsewhereon the chemical pump housing 80. In another embodiment, a valve thatoperates similarly to the first valve 92 can be disposed on the dressing14. The first valve 92 is configured to work with the mechanical pumpassembly 18. In the first operating state, the first valve 92 allows airto exit the chamber 84 through the first valve 92 when the mechanicalpump assembly 18 is inserted into the first valve 92. In the secondoperating state, the first valve 92 precludes ambient air from enteringthe chamber 84 through the upper opening 90 and first valve 92 when themechanical pump assembly 18 is not inserted into the first valve 92.Examples of such valves include, but are not limited to, a spring-biasedcheck valve and a valve comprising flaps. FIG. 5 depicts the first valve92 having flaps 94. The flaps 94 on the first valve 92 are closed beforethe mechanical pump assembly 18 is introduced into the upper opening 90.No gas is allowed to escape through the upper opening 90 and the firstvalve 92 unless the mechanical pump assembly 18 is introduced. The flaps94 on the first valve 92 return to the closed position by theirresilient forces, as the mechanical pump assembly 18 is removed.

In the illustrated embodiment, a sealing member 96 is disposed on thebottom of the chemical pump housing 80. Also, the sealing member 96 canbe disposed on a side of the chemical pump housing 80 and elsewhere onthe chemical pump housing 80. In the illustrated embodiment, the sealingmember 96 is positioned in the lower opening 86 and configured to workwith the fitting 44. The sealing member 96 allows air to enter thechamber 84 through the lower opening 86 when the chemical pump assembly16 is pressed onto and fitted with the fitting 44. The sealing member 96prevents ambient air from entering the chamber 84 when the chemical pumpassembly 16 is not fitted onto the fitting 44. FIG. 5 depicts thesealing member 96 having flaps 98. The flaps 98 on the sealing member 96are closed before the chemical pump assembly 16 is fit onto the fitting44. No gas is allowed to enter through the sealing member 96 unless theflaps 98 are moved from their initial closed position. Alternatively,the sealing member 96 can be foil or another member capable of beingpunctured when pressed against the fitting 44.

With reference to FIG. 4 , a negative pressure indicator, which in theillustrated embodiment is a diaphragm 100, may be disposed on thechemical pump housing 80 to provide an indication to the user that thesystem is under negative pressure. Referring to FIG. 4 , the diaphragm100 can be dome shaped protruding out of the chemical pump housing 80when the pressure in the chamber 84 is at or above a predeterminedpressure, which can be atmospheric pressure. The diaphragm 100 can bemade from an elastic material. As the pressure in the chemical pumpassembly 16 or dressing 14 decreases below the target pressure range,the diaphragm 100 is drawn into the chemical pump housing 80. As thediaphragm 100 is drawn towards the inside of the chemical pump housing80, the diaphragm 100 is inverted. When the diaphragm 100 is inverted,this provides an indication to the user that the system is undernegative pressure. Alternatively, the indicator can be disposed on thedressing 14.

FIGS. 6 and 7 schematically depict the mechanical pump assembly 18. Inthe illustrated embodiment, the mechanical pump assembly 18 is a singleaction vacuum source used to create negative pressure in the enclosedvolume 60 of the dressing 14. When the chemical pump assembly 16 isinitially installed on the dressing 14 (see FIG. 8 ), negative pressurein the enclosed volume 60 of the dressing 14 is not created until thechemical pump assembly 16 is in full operation, i.e., until the reactor82 scavenges the selected gas found in air from the chamber 84 and theenclosed volume 60. Therefore, the mechanical pump assembly 18 can alsoassist in the negative pressure maintenance of the dressing 14.Furthermore, the mechanical pump assembly 18 can assist in drawing thedressing 14 towards the dressing site 28.

In one embodiment, the mechanical pump assembly 18 may include amanually-actuated actuator and a biasing mechanism operatively connectedwith a movable pump element. The actuation of the manually-actuatedactuator results in the biasing mechanism moving the movable pumpelement so as to draw air into the mechanical pump assembly. In result,negative pressure is created in the enclosed volume 60. Thus, themechanical pump assembly 18 can be a pneumatic piston cylinder. Withreference to FIG. 6 , the mechanical pump assembly 18 comprises amechanical pump housing 120, and a pump chamber having a first chamber138 and a second chamber 140. An actuator 144 may be disposed on theside of the mechanical pump housing 120. The actuator 144 can bemanually operated and used to activate the operation of the mechanicalpump assembly 18. Examples of such actuators include, but are notlimited to, a button, a switch, or a trigger.

An internal wall 122 may be used to separate the first chamber 138 fromthe second chamber 140. The internal wall 122 includes a rod opening 142for accepting a piston rod 130. A seal 124 encircles the internal wall122 to prevent any gas from passing between the first chamber 138 andthe second chamber 140 around the internal wall 122. Alternatively, theinternal wall 122 can be integrally formed with the mechanical pumphousing 120. Furthermore, a second seal 146 in the rod opening 142 canenclose the piston rod 130 so that gas is prevented from passing betweenthe first chamber 138 and the second chamber 140 through the rod opening142 without restricting the movement of the piston rod 130.

The mechanical pump housing 120 includes a tip 134 disposed at thebottom. The tip 134 includes a tip opening 136 in fluid communicationwith the first chamber 138. Furthermore, the mechanical pump assembly 18can also be in fluid communication with the opening 48 on the drape 40via the hose 62 that can connect with the tip 134 or via the tipconnecting directly with the fitting 44. The hose 62 can be any length,thus a long hose 62 can be utilized. Therefore, the mechanical pumpassembly 18 can be operated on the dressing 14 before the chemical pumpassembly 16 is installed on the dressing 14. This can help seal thedressing 14 at the dressing site 28. In result, the mechanical pumpassembly 18 can directly apply reduced pressure to the dressing 14.

In the illustrated embodiment, the biasing mechanism is a spring 126,and the movable element is a piston 128. The spring 126 and the piston128 are disposed in the first chamber 138. Before the mechanical pumpassembly 18 is activated, a majority of the piston rod 130 is alsolocated in the first chamber 138. Also, a head 132 disposed on the topof the piston rod 130 is disposed in the second chamber 140. When themechanical pump assembly 18 is introduced to the first valve 92 (FIG. 9) of the chemical pump assembly 16 or connected with the fitting 44 bythe hose 62 (FIG. 3 ), the actuator 144 is used to activate theoperation of the mechanical pump assembly 18. As the mechanical pumpassembly 18 is activated, a connector 170 (see FIG. 6 ) between theactuator 144 and the piston rod 130 releases the piston rod 130, and airenters first chamber 138 of the mechanical pump housing 120 through thetip opening 136. The connector 170 can reengage the piston rod 130.Thus, the mechanical pump assembly 18 may be reusable. As depicted inFIG. 7 , the spring 126 biases the piston 128 toward the internal wall122, which draws air into the first chamber 138. The piston rod 130moves into the second chamber 140, and the head 132 moves towards thetop surface of the mechanical pump housing 120. As a result, thenegative pressure of the dressing 14 is created.

The negative pressure assembly can be susceptible to reaching a negativepressure below the target pressure range, e.g. too much vacuum ornegative pressure may be achieved in the enclosed volume 60. In order tomaintain the target pressure range, as shown in FIG. 5 , a relief valve148 may be disposed on the chemical pump housing 80 to release pressureas needed. Alternatively, a relief valve similar in operation to therelief valve 148 can be disposed on the drape 40 of the dressing 14. Therelief valve 148 can be any valve that can manually or automaticallyrelease pressure as needed. FIG. 5 depicts one embodiment in which therelief valve 148 is disposed on the chemical pump assembly 16. It is tobe understood that the relief valve 148 functions similarly in anembodiment in which the relief valve 148 is disposed on the dressing 14.Referring to FIG. 5 , the relief valve 148 comprises a flexible cap 160protruding into the chemical pump housing 80 connected with a post 162.The flexible cap 160 normally covers an opening 164. The flexible cap160 can be made from an elastic material. As a pressure differentialbetween ambient and the dressing 14 or ambient and the chamber 84 in thechemical pump assembly 16 moves outside of a predetermined pressurerange, which can be set for example between 50 mmHg and 200 mmHg, theflexible perimeter 190 of the flexible cap 160 is drawn into thechemical pump housing 80 or the drape 40. As the flexible perimeter 190of the flexible cap 160 is drawn toward the inside of the chemical pumphousing 80 or the dressing 14, a space is created around the perimeterof the flexible cap 160 so that air can pass through the opening 164.When the opening 164 is not covered by the flexible cap 160, air fromthe ambient enters the chemical pump assemble 16 or the dressing 14until the internal pressure reaches the pressure at which the perimeter190 of the flexible cap 160 relaxes onto the inner surface of thechemical pump housing 80 to reseal and close the opening 164. Thechemical pump assembly 16 and/or the dressing 14 are then subject to theamount of negative pressure at which the relief valve 148 reseals, whichcan be different than the pressure differential at which the opening 164is opened while still being within the therapeutic range, e.g., between50 mmHg and 200 mmHg.

In another embodiment, a bidirectional valve 184 is disposed on thechemical pump housing 80 instead of the first valve 192 and the releasevalve 148, as depicted in FIG. 5A. Alternatively, the bidirectionalvalve 184 can be disposed on the at least one dressing 14. In yetanother embodiment, the bidirectional valve 184 may be similarconstruction to the valve described in U.S. Pat. No. 5,439,143. Thechemical pump assembly 16 may be in fluid communication with theenclosed volume 60 through the bidirectional valve 184. Additionally,the mechanical pump assembly 18 may also be in fluid communication withthe enclosed volume 60 through the bidirectional valve 184. As depictedin FIG. 15 , the hose 62 can be attached to the mechanical pump assembly18 and inserted into the bidirectional valve 184. In result, themechanical pump assembly 18 is in fluid communication with the enclosedvolume 60.

The bidirectional valve 184 may include three operating states. In thefirst operating state, gas is allowed to exit the chamber 84 and/or theenclosed volume 60 through the bidirectional valve 184 when the externalpressure is below that of the enclosed volume 60 and/or the chamber 84.In the second operating state, the bidirectional valve 184 precludes gasfrom entering or exiting the enclosed volume 60 and/or the chamber 84through the bidirectional valve 184 when the pressure of the chamber 84and/or the enclosed volume 60 is between the first predeterminedthreshold and a second predetermined threshold. In the third operatingstate, the bidirectional valve 184 allows gas from ambient to enter theenclosed volume 60 and/or the chamber 84 through the bidirectional valve184 when the pressure in the enclosed volume 60 and/or the chamber 84 isbelow the predetermined threshold. In one embodiment, the predeterminedthreshold is 560 mmHg or 200 mmHg below atmospheric. In yet anotherembodiment, the bidirectional valve 184 may include springs thatautomatically actuate the bidirectional valve 184 when a pressuredifferential is at the first or second predetermined threshold.

In still another embodiment, the mechanical pump assembly 18 isconnected to multiple dressings. Furthermore, the mechanical pumpassembly 18 can be connected to the multiple dressings at the same time.For example, the mechanical pump assembly 18 can be connected to asecond dressing 188. The hose 62 can include a Y-shaped fitting 186 toconnect the mechanical pump assembly 18 to the dressing 14 and thesecond dressing 188 at the same time. Furthermore, the chemical pumpassembly 16 can also be connected to multiple dressings and can beconnected to the multiple dressings at the same time. As depicted inFIG. 14 , the hose 62 can include the Y-shaped fitting 186 tosimultaneously connect the chemical pump assembly 16 to the dressing 14and the second dressing 188.

A method for achieving negative pressure therapy with the negativepressure kit 10 will be described hereinafter. First, at least onedressing 14 is removed from the tray kit 12, and the drape release lineris removed to expose the adhesive 66 on the bottom surface of the drapeedge 54. The drape edge 54 is placed on skin S around at least onedressing site 28 and is secured to the skin S by the adhesive 66.

With reference to FIG. 8 , the drape 40 is secured over the dressingsite 28, and the second valve 96 on the chemical pump assembly 16 isintroduced to the fitting 44 on the drape 40. The second valve 96 isplaced over the fitting 44, and the flaps 98 are opened. When the flaps98 are open, the chemical pump assembly 16 is in fluid communicationwith the dressing 14. The reactor 82 begins to consume the selected gasfrom the enclosed volume 60 but is not complete at this time.

Afterwards, the mechanical pump assembly 18 is inserted into the firstvalve 92 disposed on the chemical pump assembly 16 to open the flaps 94,as depicted in FIG. 9 . As the flaps 94 are opened, the mechanical pumpassembly 18 is in fluid communication with the chamber 84 in thechemical pump assembly 16. Alternatively, the mechanical pump assembly18 is inserted into the bidirectional valve 184. Also, the mechanicalpump assembly 18 is in fluid communication with the enclosed volume 60via the chemical pump assembly 16. When the mechanical pump assembly 18is in fluid communication with the chemical pump assembly 16, theactuator 144 is used to activate the operation of the mechanical pumpassembly 18, as depicted in FIG. 10 . Then, the spring 126 pushes thepiston 128 towards the internal wall 122. As the piston 128 moves, airenters the first chamber 138 of the mechanical pump assembly 18, and thedressing 14 is drawn toward the skin S. The mechanical pump assembly 18is then removed, and the flaps 94 of the first valve 92 are closed bytheir resilient forces, as depicted in FIG. 11 . In the embodiment withthe bidirectional valve 184, the bidirectional valve 184 moves to thesecond operating state, as the mechanical pump assembly 18 is removedfrom the bidirectional valve 184. The reactor 82 in the chemical pumpassembly 16 can continue to apply or maintain reduced pressure to thedressing 14. In result, the pressure in the dressing 14 is reduced to anegative pressure, and the negative pressure indicator 100 signals whenthe negative pressure has been achieved. At any time the reducedpressure decreases below a target pressure range, the relief valve 148or the bidirectional valve 184 releases pressure as needed to restorethe reduced pressure to a predetermined pressure differential.

In another embodiment, the mechanical pump assembly 18 can be insertedprior to the chemical pump assembly 16. First, the at least one dressing14 is placed and secured over the at least one dressing site 28. Then,the mechanical pump assembly 18 is connected to the fitting 44 on thedressing 14 by the hose 62. Alternatively, the first valve 92 orbidirectional valve 184 is disposed on the dressing 14 instead of thechemical pump assembly 16 to provide direct fluid communication betweenthe dressing 14 and the mechanical pump assembly 18. As a result, themechanical pump assembly 18 is in fluid communication with the enclosedvolume 60. The first valve 92 or bidirectional valve 184 may furtherreplace the fitting 44. In these alternate embodiments, the mechanicalpump assembly 18 is inserted into the first valve 92 or thebidirectional valve 184 on the dressing 14.

After the mechanical pump assembly 18 is connected to the dressing 14,the mechanical pump assembly 18 is activated with the actuator. Inresult, the piston 128 moves toward the internal wall 122, and airenters the first chamber 138 of the mechanical pump assembly 18. Themechanical pump assembly 18 is removed and replaced by the chemical pumpassembly 16. The reactor 82 in the chemical pump assembly 16 beginsreacting with a selected gas found in air to maintain the negativepressure of the dressing. When the negative pressure in the enclosedvolume 60 is achieved, the indicator on the dressing 14 and/or thechemical pump assembly 16 signals when the dressing 14 reaches anegative pressure. As needed, the relief valve 148 or the bidirectionalvalve 184 releases pressure when the reduced pressure decreases below atarget pressure range.

In still another embodiment, the chemical pump assembly 16 and themechanical pump assembly 18 are both connected to the at least onedressing 14. In this embodiment, a first valve, fitting, or hose and asecond valve, fitting or hose are disposed on the dressing 14. Thechemical pump assembly 16 is connected to the dressing via the firstvalve, fitting, or hose. The mechanical pump assembly 18 is connectedfor the second valve, fitting, or hose. For example, the chemical pumpassembly 16 is connected to the dressing 14 via the fitting 44 disposedon the dressing 14, while the mechanical pump assembly 18 is connectedto the dressing 14 via the hose 62 and a second fitting 166 disposed onthe dressing 14, as depicted in FIG. 12 . Also, in particular when thedressing 14 that includes at least one relief valve similar to therelief valve 148 described above, the chemical pump assembly 16 could bereplaced with an electro-mechanical pump similar to those now used withknown negative pressure wound therapy devices. Different than knownnegative pressure wound therapy devices, however, the relief valve(s) onthe dressing 14 can open and close (as described above) to maintain theenclosed volume underneath the dressing within the therapeutic range.Also, in lieu of the relief valves, the dressing 14 could include abidirectional valve similar to the bidirectional valve 184 that couldcooperate with the mechanical pump assembly 18 while anelectro-mechanical pump similar to those now used with known negativepressure wound therapy devices could connect with the fitting 44 shownin FIG. 12 .

Furthermore, at least one attachment can be disposed on the mechanicalpump assembly 18 or the chemical pump assembly 16 for storing the hose62. An example of such an attachment is, but is not limited to, a wrapelement. With reference to FIG. 13 , the chemical pump assembly 16 mayinclude a wrap element 176 disposed on the chemical pump housing 80around which the hose 62 can be wound. Alternatively, the wrap element176 can be disposed on the mechanical pump housing 120. The hose 62 canbe coiled around the at least one attachment so that the hose 62 issecured during storage and transportation. In another embodiment, thehose 62 can retract into the chemical pump assembly 16. In yet anotherembodiment, the hose 62 can retract into the mechanical pump assembly18. Alternatively, the tray kit 12 can include an additional recess forstoring the hose 62.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives or varieties thereof, may bedesirably combined into many other different systems or applications.Also that various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

The invention claimed is:
 1. A negative pressure assembly comprising: adrape for covering a dressing site on a patient and capable ofmaintaining a negative pressure underneath the drape when sealed againstskin upon application of a vacuum; a sealing element that when appliedto the skin cooperates with the drape to define an enclosed volumecovered by the drape and surrounded by the sealing element; a reactorlocated with respect to the drape and the sealing element so as to be influid communication with the enclosed volume when the drape is coveringthe dressing site, the reactor being configured to react with a selectedgas found in air so as to consume the selected gas; a mechanical pumpassembly including a pump chamber fluidly connectable to the enclosedvolume, and configured to draw air from the enclosed volume into thepump chamber when fluidly connected with the enclosed volume; and achemical pump assembly including a chemical pump housing and the reactorpositioned in a chamber of the chemical pump housing, wherein themechanical pump assembly is connectable to the chemical pump assembly sothat the pump chamber is in fluid communication with the enclosed volumevia the chemical pump assembly.
 2. The negative pressure assembly ofclaim 1, further comprising a dressing including an absorbent materialand the drape.
 3. The negative pressure assembly of claim 2, furthercomprising a relief valve on the dressing in fluid communication withthe enclosed volume and ambient, the relief valve being configured toallow gas from ambient to enter the enclosed volume through the reliefvalve when a pressure differential between ambient and the enclosedvolume is outside a predetermined pressure range.
 4. The negativepressure assembly of claim 1, wherein the chemical pump assembly isconnectable with the dressing via a fitting, such that the chamber ofthe chemical pump housing is in fluid communication with the enclosedvolume.
 5. The negative pressure assembly in claim 1, further comprisinga diaphragm on the chemical pump housing configured to move toward thechamber of the chemical pump housing when the chamber is under negativepressure.
 6. The negative pressure assembly in claim 1, wherein themechanical pump assembly is connectable to the chemical pump housing viaa valve, a fitting, or a hose.
 7. The negative pressure assembly inclaim 6, wherein the valve is configured to allow gas to exit throughthe valve and into the pump chamber and to prevent ambient air fromentering the chamber of the chemical pump housing through the valve. 8.The negative pressure assembly of claim 1, further comprising a reliefvalve on the chemical pump housing in fluid communication with thechamber of the chemical pump housing and ambient, the relief valve beingconfigured to allow gas from ambient to enter the chamber through therelief valve when a pressure differential between ambient and thechamber is outside a predetermined pressure range.
 9. The negativepressure assembly in claim 1, wherein the chemical pump assembly isconnectable to a second dressing covering a second dressing site via avalve, a fitting, or a hose.
 10. A negative pressure assembly,comprising: a drape for covering a dressing site on a patient andcapable of maintaining a negative pressure underneath the drape whensealed against skin upon application of a vacuum; a sealing element thatwhen applied to the skin cooperates with the drape to define an enclosedvolume covered by the drape and surrounded by the sealing element; areactor located with respect to the drape and the sealing element so asto be in fluid communication with the enclosed volume when the drape iscovering the dressing site, the reactor being configured to react with aselected gas found in air so as to consume the selected gas; amechanical pump assembly including a pump chamber fluidly connectable tothe enclosed volume, and configured to draw air from the enclosed volumeinto the pump chamber when fluidly connected with the enclosed volume,and a chemical pump assembly including a chemical pump housing and thereactor positioned in a chamber of the chemical pump housing, whereinthe mechanical pump assembly is connectable to the chemical pumpassembly so that the pump chamber is in fluid communication with theenclosed volume via the chemical pump assembly, wherein the mechanicalpump assembly includes a manually-actuated actuator and a biasingmechanism operably connected with a movable pump element, whereinactuation of the manually-actuated actuator results in the biasingmechanism moving the movable pump element so as to draw air into themechanical pump assembly.
 11. The negative pressure assembly of claim10, further comprising a relief valve on the chemical pump housing influid communication with the chamber of the chemical pump housing andambient, the relief valve being configured to allow gas from ambient toenter the chamber of the chemical pump housing through the relief valvewhen a pressure differential between ambient and the chamber of thechemical pump housing is outside a predetermined pressure range.